Seizure detection based on work level excursion

ABSTRACT

We report a method of determining an occurrence of an epileptic convulsive seizure in a patient, comprising: receiving body data from a patient during a first time period, determining a work level relating to said first time period at least based partially upon said body data; determining whether said work level exceeds an extreme work level threshold; performing a responsive action, in response to a determination that said work level exceeds said extreme work level threshold. We also report a medical device system configured to implement the method. We also report a non-transitory computer readable program storage unit encoded with instructions that, when executed by a computer, perform the method.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit under 35 U.S.C. §119(e) ofprior-filed provisional applications 61/785,429, filed Mar. 14, 2013;and 61/798,274, 61/793,292, 61/794,540, and 61/801,950, all filed Mar.15, 2013, and is a continuation-in-part of U.S. patent application Ser.No. 14/084,513, filed Nov. 19, 2013, the disclosures of which are herebyincorporated by reference.

FIELD OF THE INVENTION

This disclosure relates to medical device systems and methods capable ofdetecting epileptic seizures.

SUMMARY OF THE INVENTION

In some embodiments, the present disclosure relates to a method ofdetermining an occurrence of an epileptic convulsive seizure in apatient, comprising: receiving body data from a patient during a firsttime period, determining a work level relating to said first time periodat least based partially upon said body data; determining whether saidwork level exceeds an extreme work level threshold; performing aresponsive action, in response to a determination that said work levelexceeds said extreme work level threshold, wherein said responsiveaction is selected from: determining said occurrence of said convulsiveseizure, or implementing a confirmation test to confirm said occurrenceof said epileptic convulsive seizure. In some embodiments, the presentdisclosure relates to a method of determining an occurrence of anepileptic seizure in a patient, comprising receiving body data from apatient during a first time period, determining a work level relating tosaid first time period at least based partially upon said body data;determining an activity level of said patient during said first timeperiod; determining whether said work level is incommensurate with saidactivity level; and determining said occurrence of said epilepticseizure, based at least in part on said incommensurateness of said worklevel with said activity level.

In other embodiments, the present disclosure relates to a medical devicesystem, comprising at least one sensor, each configured to collect atleast one body signal from a patient relating to a work level of saidpatient; and a medical device, comprising: a body data module configuredto receive body data; a patient state data unit configured to determinethe patient state based upon said body data; a work level data moduleconfigured to determine a patient's first work level during a first timeperiod, and the patient's second work level during a second time period;a work level excursion module configured to determine a work levelexcursion threshold based at least one said body data, time of day, orsaid patient state; a work level excursion test module configured todetermine whether said second work level exceeds said first work levelby greater than an amount of said first work level excursion threshold;and a controller to perform at least one of warning of a pathologicalstate, providing a therapy, or logging said occurrence of saidpathological state.

In some embodiments, the present disclosure relates to a method ofdetermining a work level of a subject's brain, comprising: determining afirst oxygen saturation, concentration, or pressure of the subject'sblood at a first location in an artery; determining a second oxygensaturation, concentration, or pressure of the subject's blood at asecond location in a vein or venous sinus; and determining the worklevel of the subject's brain based on said first oxygen saturation,concentration, or pressure and said second oxygen saturation,concentration, or pressure.

In other embodiments, the present disclosure relates to a medical devicesystem, comprising: a first sensor configured to collect first oxygensaturation, concentration, or pressure data of a subject's blood from afirst location in an arterial vessel; a second sensor configured tocollect second oxygen saturation, concentration, or pressure data of thesubject's blood from a second location in a venous structure; and amedical device, comprising: a first location oxygen saturation,concentration, or pressure module configured to determine a first oxygensaturation, concentration, or pressure from said first oxygensaturation, concentration, or pressure data; a second location oxygensaturation, concentration, or pressure module configured to determine asecond oxygen saturation, concentration, or pressure from said secondoxygen saturation data; an oxygen saturation, concentration, or pressuredifference module configured to determine a difference between the firstoxygen saturation, concentration, or pressure and the second oxygensaturation; and a brain work level determination module configured todetermine a work level of the subject's brain based on the difference.

In some embodiments, the present disclosure relates to a method ofdetermining a work level of a subject's body, comprising: determining afirst oxygen saturation, concentration, or pressure of the subject'sarterial blood at a first location selected from one of a leftventricle, an aorta, a branch of the aorta, or a sub-branch of theaorta; determining a second oxygen saturation, concentration, orpressure of the subject's venous blood at a second location in a bloodvessel selected from one of a superior vena cava, an inferior vena cava,a right ventricle, a pulmonary artery, or a jugular vein; anddetermining the work level of the subject's body or body parts based onthe difference.

In other embodiments, the present disclosure relates to a medical devicesystem, comprising: a first sensor configured to collect first oxygensaturation, concentration, or pressure data of the subject's arterialblood from a first location selected from a left ventricle, an aorta, abranch of the aorta, or a sub-branch of the aorta; a second sensorconfigured to collect second oxygen saturation, concentration, orpressure data of a subject's venous blood from a second location in ablood vessel selected from a superior vena cava, an inferior vena cava,a right ventricle, a pulmonary artery, or a jugular vein; and a medicaldevice, comprising: a first location oxygen saturation, concentration,or pressure module configured to determine a first oxygen saturation,concentration, or pressure from said first oxygen saturation,concentration, or pressure data; a second location oxygen saturation,concentration, or pressure module configured to determine a secondoxygen saturation, concentration, or pressure from said second oxygensaturation, concentration, or pressure data; and a body or body partswork level determination module configured to determine a work level ofthe subject's body or body parts based on the first oxygen saturation,concentration, or pressure and the second oxygen saturation,concentration, or pressure.

In some embodiments, the present disclosure relates to a non-transitorycomputer readable program storage unit encoded with instructions that,when executed by a computer, perform a method as described above.

DESCRIPTION OF THE DRAWINGS

The disclosure may be understood by reference to the followingdescription taken in conjunction with the accompanying drawings, inwhich like reference numerals identify like elements, and in which:

FIG. 1 shows a schematic diagram of a medical device system, inaccordance with some embodiments of the present disclosure;

FIG. 2 shows a schematic diagram of portions of a medical device system,in accordance with some embodiments of the present disclosure;

FIG. 3 shows a schematic diagram of a work level data module, accordingto some embodiments of the present disclosure;

FIG. 4 shows a variation of work level range over the course of a day,according to some embodiments of the present disclosure;

FIG. 5 shows a schematic diagram of a patient state data unit, accordingto some embodiments of the present disclosure;

FIG. 6 shows a flowchart depiction of a method, according to someembodiments of the present disclosure; and

FIG. 7A shows a flowchart depiction of some steps of the method of FIG.7, according to some embodiments of the present disclosure;

FIG. 7B shows a flowchart depiction of some steps of the method of FIG.7, according to some embodiments of the present disclosure;

FIG. 8 shows a flowchart depiction of a method, according to someembodiments of the present disclosure;

FIG. 9A shows a flowchart depiction of a method of measuring the worklevel of the patient's body or a part thereof, according to someembodiments of the present disclosure;

FIG. 9B shows a flowchart depiction of a method of measuring the worklevel of the patient's body or a part thereof, according to someembodiments of the present disclosure;

FIG. 10A qualitatively shows the typical correspondence between activitylevel and work level for convulsive seizures, according to someembodiments of the present disclosure;

FIG. 10B qualitatively shows a typical correspondence betweennon-seizure activity level and non-seizure work level, according to someembodiments of the present disclosure;

FIG. 10C qualitatively shows a typical lack of correspondence betweennon-seizure activity level and seizure work level, for both partial andconvulsive seizures, according to some embodiments of the presentdisclosure; and

FIG. 11 shows a flowchart depiction of a method of detecting a seizure,according to some embodiments of the present disclosure.

While the disclosure is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the disclosure to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the disclosure as defined by the appended claims.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Illustrative embodiments of the disclosure are described herein. Forclarity, not all features of an actual implementation are described. Inthe development of any actual embodiment, numerousimplementation-specific decisions must be made to achievedesign-specific goals, which will vary from one implementation toanother. Such a development effort, while possibly complex andtime-consuming, would nevertheless be a routine undertaking for personsof ordinary skill in the art having the benefit of this disclosure.

Some embodiments disclosed herein provide for performing a convulsiveseizure detection based upon a work level of a patient. Body signal(s)from a patient, such as arterio-venous differences in oxygen, may beacquired during a first time period. Based at least partially upon thebody signal(s), a work level of the patient for the first time period isdetermined. A determination can then be made as to whether the worklevel exceeds an extreme work level threshold or some other non-extremereference level value. If the work level exceeds an extreme threshold, adetermination that a convulsive seizure has occurred may be made.Further, a confirmation test to confirm the convulsive seizure may beperformed.

“Work level” herein refers to the energy consumption of the patient'sbody or a part thereof (e.g., the brain). Energy consumption may, insome embodiments, be measured by differences in oxygen saturation,concentration, or pressure between arterial and venous locations. Insome embodiments of this disclosure, work level may be determined usingmeasures of kinetic activity (force, amplitude, velocity, direction, andduration and rate of muscle contractions) or autonomic activity such asheart rate. “Work level” in this disclosure does not refer exclusivelyto the patient's physical activity. Physical activity may be only one ofmultiple physiological events or states leading to energy consumption bythe patient's body or a part thereof “Work level” may also refer to thephysics definition, W=F×d. The application of force over distance may beonly one of multiple actions by a patient leading to energy consumptionby the patient's body or a part thereof.

One of the meanings of extreme work level herein is a work level thatcannot be accomplished volitionally. Extreme work levels may exceed themaximal volitional work level that may be performed by the patient perunit time, and/or may exceed the total duration of a work that could besustained volitionally by a patient. Convulsive (generalized tonic orclonic or tonic-clonic) seizures are associated with a work level(determined using metabolic, kinetic or other signals) that is extreme.

FIG. 10A illustrates, in qualitative fashion, typical correspondence orcommensurateness between ranges (minimum to maximum) of activity andwork levels for non-seizure conditions, e.g., from sleep up to maximalvolitional exercise. It further illustrates that while the activity andwork levels for convulsive seizures are much greater than fornon-seizures, these levels are still commensurate.

FIG. 10B illustrates, in qualitative fashion, typical commensuratenessbetween activity and work levels for non-seizure or interictal periodsfor a typical patient.

FIG. 10C depicts, in qualitative fashion, typical differences betweennon-seizure activity level and seizure work level. Notice that while thework level for partial seizures is generally within the non-seizureactivity level range, it is incommensurate with the current (e.g., atthe time(s) the change in work level occurs) non-seizure activity level.The work level of epileptic convulsive seizures is well above thenon-seizure activity level range. On the other hand, the work level ofgeneralized atonic seizures and partial seizures manifesting withmotionlessness or with bradycardia may be below the non-seizure activityrange and/or incommensurate with the current non-seizure activity level.Thus, “incommensurateness” as used herein may be observable by a worklevel outside an expected work level range, above an upper work levelthreshold, and/or below a lower work level threshold.

In another embodiment of the present disclosure, a pathological state ofa patient may be detected based upon an excursion of a work level of thepatient. The excursion may relate to an increase in a work level duringa second time period compared to a work level during a first timeperiod. Body signal(s) from a patient may be acquired during a firsttime period. Based at least partially upon the body signal(s), a firstwork level of the patient for the first time period is determined. Bodysignal(s) from a patient may be acquired during a second time period.Based at least partially upon the body signal(s), a second work level ofthe patient for the second time period is determined. The first andsecond work levels are compared and a determination is made whether thesecond work level exceeds the first work level by a work level excursionthreshold.

In one embodiment, if the second work level exceeds the first work levelby a certain quantity that may be set as a threshold, a pathologicalstate may be deemed to have occurred. In general, a threshold may be setin a relative or absolute manner dependent upon the context and clinicalapplication of the situation. In another embodiment, if the second worklevel does not exceed the first work level but said work level isincommensurate with the on-going activity levels (e.g., too high or toolow a work level relative to a work level expected for the patient'sactivity level), a pathological state may be deemed to have occurred.

In response to detecting the pathological state, a responsive action maybe taken, wherein the responsive action may include providing a warning(e.g., locally (at the site where the patient is located at the time ofthe convulsion) and/or remotely (to an EMT, a doctor's office, a nurse'sstation, etc.), providing a therapy, and/or logging the occurrence ofthe pathological event and its characteristic (e.g., severity,prevailing conditions at date/time of occurrence, etc.). Theenvironmental factors surrounding the occurrence of the pathologicalevent may also be logged and taken into account into the determinationof the pathological event. In an alternative embodiment, the aboveanalyses may be performed by using a moving window to acquire body datasignals. In one embodiment, the work level excursion threshold may bedetermined based upon at least one of the body signal acquired duringthe first time period or the work level during the first time period.

Determination of the value of the extreme work level threshold wouldallow classification of seizures into convulsive and non-convulsive(e.g. partial): Work levels that reach or exceed the extreme thresholdcorrespond to convulsions (e.g., generalized tonic, tonic-clonic,clonic-tonic-clonic or myoclonic) and those associated with work levelsthat are incommensurate with corresponding activity levels but remainbelow the extreme threshold, correspond to partial seizures. That is,work level excursions or degree of incommensurateness between activitylevel and work level may be used in one or more embodiments in thisdisclosure, to detect and quantify seizures and to classify them asepileptic or non-epileptic (in the case of convulsive seizures) and theepileptic seizures as convulsive or non-convulsive (e.g., partial).Moreover, these two observables may be used to distinguish inter-ictalfrom the ictal and post-ictal states.

FIG. 1 shows a schematic representation of a medical device system,according to some embodiments of the present disclosure. The medicaldevice system 100 may comprise a medical device 200, body data sensor(s)112, and lead(s) 111 coupling the sensor(s) 112 to the medical device200. In one embodiment, body data sensor(s) 112 may each be configuredto collect data from a patient relating to a time series of body datavalues. In one embodiment, the body data may be selected from heartrate, blood pressure, respiratory rate, dermal activity, oxygensaturation, or end-tidal CO₂ among others.

“Oxygen saturation” is used herein to encompass measures of oxygen inthe patient's blood. Such measures include O₂ concentration and O₂partial pressure, among others. In yet other embodiments, glucose or ATPconsumption or production of certain byproducts of metabolism, such asCO₂ or lactic acid, may be used to determine work level in the brain,other body parts (e.g., muscles), or the body as a whole.

Various components of the medical device 200, such as controller 110,processor 115, memory 117, power supply 130, communication module 140,warning unit 192, therapy unit 194, logging unit 196, and severity unit198 have been described in other patent applications assigned to FlintHills Scientific, LLC or Cyberonics, Inc., such as, U.S. Ser. No.12/896,525, filed Oct. 1, 2010; U.S. Ser. No. 13/288,886, filed Nov. 3,2011; U.S. Ser. No. 13/449,166, filed Apr. 17, 2012; and U.S. Ser. No.13/678,339, filed Nov. 15, 2012. Each of the patent applicationsidentified in this paragraph is hereby incorporated herein by reference.

The medical device 200 may comprise at least one therapy delivery source(e.g., electrode or catheter) 114, configured to deliver an electricalstimulation or some other form of therapy (e.g., a drug) to a tissue ofthe patient, such as a neural tissue of the patient. An exemplaryelectrical stimulation therapy is vagus nerve stimulation therapy, suchas that provided by implantable VNS devices commercially available fromCyberonics, Inc. Alternatively or in addition, pharmacological, thermal,or other therapies may be used in this disclosure.

The medical device 200 may comprise a body data module 175 configured toreceive body data from the at least one sensor(s) 112.

The medical device 200 may comprise a patient's state data unit 160configured to determine a patient's state based upon one or more of thebody data, the time of day, or an activity level history of the patient,among others. A patient's state may be selected from one or more ofasleep or awake, resting or active, etc.

The medical device 200 may comprise an activity level module 162configured to determine the patient's activity level based at least inpart on one or more of the body data, the time of day, or an activitylevel history of the patient. The patient activity level differs frompatient state by being more short-term in focus and more immediately (inthe temporal sense) derived from its inputs. For example, a patient inthe awake state may be motionless or active ranging from slow walking tovigorous exercise. These activity levels may change withinseconds/instantaneously and their determination is far more susceptibleto rapid changes than is the case for a patient that may be continuouslyin an awake state for 12-16 hours per day. That said, there may occurcircumstances wherein the patient activity level and the patient stateprovide nearly the same information, e.g., when the patient is asleep.

The medical device 200 may comprise and environmental conditionsdetermination module 164 configured to determine one or moreenvironmental conditions (e.g., time of day, ambient temperature,altitude, ambient humidity, barometric pressure, luminance, etc.). Oneor more of the determined environmental conditions may be provided toother component(s) of the medical device 200, e.g., the patient statedata unit 160, the activity level module 162, etc., to allowdeterminations of patient state, activity level, etc. to be based atleast in part on the one or more determined environmental conditions.

The medical device 200 may comprise a work level data module 150configured to determine a patient's work level. For example, the worklevel data module 150 may be configured to determine a first work levelof the patient during a first time period, and the patient's second worklevel during a second time period.

The medical device 200 may comprise a time-based work level excursionmodule 170 configured to determine a work level expected for a patientat a given time of day, week, month, season, or year. In someembodiments, the time-based work level excursion module 170 maydetermine the work level expected for a patient based at least in parton at least one of body data or patient state, in addition to time ofday, etc.

The medical device 200 may comprise a work level excursion module 180configured to determine whether a work level is undergoing a work levelexcursion indicative of a seizure. For example, the work level excursionmodule 180 may determine if a work level exceeds an extreme work levelthreshold. In some embodiments, the work level excursion module 180 maydetermine an extreme work level threshold, such as at a value of threestandard deviations above the patient's mean or median work level. Thismean may be determined over any time scale (e.g., 1-10 sec.; 11 sec-1hr; up to 24 hr or more than 24 hr), up to all available data for thepatient. In some embodiments, the extreme work level threshold may beset at an elevated level (e.g., more than three standard deviations) orat a lowered level (e.g., less than three standard deviations) from aparticular body data state for the patient, such as moderate orstrenuous exercise. Other statistical markers (e.g., percentiles) may beused instead of, or in addition, to the mean or median.

For another example, in some embodiments, the work level excursionmodule 180 may determine the work level expected for a patient based onat least one of body data, time of day, or patient state. In light of adetermined expected work level, the work level excursion module 180 maydetermine if a second work level exceeds a first work level by greaterthan an amount of a first work level excursion threshold. The first worklevel excursion threshold may be pre-specified and fixed, or adaptive orvariable based on factors such as those given elsewhere. For yet anotherexample, the work level excursion module 180 may determine if anobserved work level is incommensurate with the patient's activity level.The patient's activity level may be determined by activity level module162 described above.

A work level excursion relative to a first work level excursionthreshold and/or a range expected for a patient's activity level may beconsidered an indication of a pathological state, such as a partialepileptic seizure, or a convulsive epileptic seizure.

An extreme work level excursion (beyond an extreme work level threshold)may be considered an indication of a convulsive epileptic seizure.

If a seizure is indicated by a work level excursion, in one embodiment,the controller 110 may be configured to perform at least one responsiveaction, in response to a determination that said work level excursion isindicative of a seizure, wherein said responsive action is selected fromdetermining said occurrence of said seizure, or implementing aconfirmation test to confirm said occurrence of said seizure.

FIG. 2 shows a schematic representation of components of the medicaldevice system, particularly, body data module 175 of medical device 200,as well as an autonomic data acquisition unit 260, a neurological dataacquisition unit 270, an endocrine data acquisition unit 273, ametabolic data acquisition unit 274, a tissue stress marker dataacquisition unit 275, and a physical fitness/integrity data acquisitionunit 276. In other, non-depicted embodiments, the medical device systemmay comprise none, one, or some of the data acquisition units 260-276.More information regarding multiple body data types, data collectionthereof, and use thereof in epileptic event detection may be found inother patent applications assigned to Flint Hills Scientific, LLC orCyberonics, Inc., such as, U.S. Ser. No. 12/896,525, filed Oct. 1, 2010,now U.S. Pat. No. 8,337,404, issued Dec. 25, 2012; U.S. Ser. No.13/098,262, filed Apr. 29, 2011; U.S. Ser. No. 13/288,886, filed Nov. 3,2011; U.S. Ser. No. 13/554,367, filed Jul. 20, 2012; U.S. Ser. No.13/554,694, filed Jul. 20, 2012; U.S. Ser. No. 13/559,116, filed Jul.26, 2012; and U.S. Ser. No. 13/598,339, filed Aug. 29, 2012. Each of thepatent applications identified in this paragraph is hereby incorporatedherein by reference.

Of interest in FIG. 2 is force sensing unit 291 configured to determinean amount of force generated by part or all of a patient's body.

Also of interest in FIG. 2 is blood gases acquisition unit 265. In someembodiments, blood gases acquisition unit 265 may be configured todetect blood oxygen saturation, concentration, or pressure at one ormore points in a patient's vasculature, (e.g., carotid artery, jugularvein, superior vena cava, inferior vena cava, a left ventricle of theheart, right ventricle of the heart, aorta, branch of the aorta, or asub-branch of the aorta, among others). In alternative embodiments,blood gases acquisition unit 265 may be configured to detect bloodoxygen saturation, concentration, or pressure in other blood vesselsand/or organ target sites of the patient's body. In some embodiments,blood gases unit 265 may comprise an arterio-venous oxygen differencedetermination unit 2741 configured to determine an arterio-venous oxygendifference, and an oxygen consumption determination unit 2742 configuredto determine an oxygen consumption from the arterio-venous oxygendifference. In yet other embodiments, CO₂ pressures or concentrationsmay be measured at one or more body locations.

FIG. 3 shows a work level data module 150 (e.g., such as that in FIG. 1)in more detail. The work level data module 150 may receive one or bothof body data and activity data from the patient.

The work level data module 150 may comprise a body data analysis module310 configured to analyze received body data for use by other componentsof the work level data module 150 or other modules or units of medicaldevice 200.

The work level data module 150 may comprise a work level determinationunit 320 configured to determine a work level of a patient from one ormore of the received body data or the received activity data. In oneembodiment, the work level determination unit 320 may be configured todetermine a work level of a patient from body data related to oxygenconsumption. Alternatively or in addition, the work level determinationunit 320 may be configured to determine a work level of a patient fromdata related to kinetic activity, cognitive activity, emotionalactivity, or other patient activity.

The work level data module 150 may comprise a work level-activitycorrelation module 330 configured to determine a correlation between thework level determined by work level determination unit 320 and certainreceived body signals data. This correlation may be useful as a check onthe determination of the patient's work level by work leveldetermination unit 320 (e.g., is the determined work level expected orwithin non-pathological limits based on the current activity?) and/ormay be informative regarding excursions of the patient's work level fromthat expected based on the activity. The work level-activity correlationmodule 330 may provide information regarding acceptable work leveldeviations. In addition, a work-level correlation with activity levelmay be either a positive or negative correlation or may have a strong orweak association. Further, a work correlation evaluation with anactivity level may show no correlative value (i.e., a zero correlation).

The work level data module 150 may output one or more of work level dataor acceptable work level deviation data commensurate with the activitylevel, among others. FIG. 4 shows a typical variation of work level overtime of day for an exemplary patient. Generally, an instantaneous bodywork level (WL) may be at its lowest during sleep, moderate during mostwaking hours, and high during certain waking hours, e.g., during aerobicexercise, such as the hypothetical patient of FIG. 4 is performing atabout 9 pm.

As instantaneous work level increases, the thresholds for a work levelexcursion indicative of a partial or non-convulsive seizure may vary aswell. The work level excursion may be a magnitude excursion, a rate ofchange excursion, or both. FIG. 5 shows a patient state data unit 160 inmore detail. The patient state data unit 160 may receive body dataand/or patient input (e.g., manual input). The patient state data unit160 may comprise a body data—activity correlation unit 510 configured tofind which activity may be correlated with which body datacharacteristics or properties. For example, if the body data is kineticdata and indicative of long, rhythmic strides (e.g., the patient isjogging or running) this activity may be correlated with certain heartrate, oxygen consumption or tidal respiratory volume data.

Generally, measurements of body work level may be useful for detectionof epileptic convulsive seizures. Measurements of brain oxygenconsumption may be useful for detection of both convulsive and partialseizures, for distinguishing between convulsive and partial seizures,and for distinguishing unilateral from bilateral partial seizures. Acorrelation or commensurateness of autonomic and/or other body signalwith work level may also be useful to detect partial seizures.

The patient state data unit 160 may comprise a patient input unit 520configured to receive patient manual input regarding the patient'sactivity or other parameters.

The patient state data unit 160 may comprise a background activity—timeperiod module 530 configured to determine a background activity level ator over a given time period. The determination made by the backgroundactivity—time period module 530 may comprise looking up relevantbackground activity and/or time period data stored in a table 540. Thebackground activity level may be useful for detection of bothgeneralized and partial seizures using O₂ consumption given byarterio-venous differences in oxygen saturation measured at theappropriate anatomical sites.

In some situations, heart rate, heart rhythm, respiratory rate,respiratory rhythm/pattern, etc. may serve as proxies of activity level.

The patient state data unit 160 may output patient state data for use byother modules or units of the medical device 200.

FIG. 6 shows a flowchart representation of a method 600 according tosome embodiments of the present disclosure. This method may be useful indetecting partial seizures from work level data. Body data, such asthose types discussed supra, may be received at 610. A first work levelmay be determined at 620 based at least in part on the body data.Patient state data may be received at 630. In some embodiments,receiving patient state data at 630 is optional and need not beperformed. In some situations, the patient state data may be inferredwith high confidence, and without the need for receiving it, from thebody data and/or other considerations. For example, if the patient has avery low activity level at a time between about midnight and 6:00 am, itmay be inferred with high confidence that the patient is asleep.

Based at least in part on one or more of the received body data and thereceived patient state data, one or more work level excursions may bedetermined at 640. The work level excursion(s) may be relative to athreshold, outside a non-seizure range, or absolute (e.g., independentof a threshold or range). The non-seizure work level range may bedefined at its lower bound by the patient's work level during stage 3(slow-wave) sleep and at its upper bound by the patient's maximalvolitional exertion (e.g., during intense exercise).

Similarly to and associated with the first work level determination at620, a second work level may be determined at 645.

FIG. 7A shows one embodiment of determining a work level excursionthreshold at 640 in more detail. A patient state may be determined at710 a, based on one or more of body data gathered from the patient, thetime of day, the patient's activity history, the patient's currentactivity, and/or other factors. In light of the determined patientstate, an expected work level may be determined at 760 a. The expectedwork level may include statistical measures of central tendency, highpercentile value, low percentile value, standard deviation, etc.,relating to the expected work level.

From the expected work level, a work level threshold may be determinedat 770 a. The work level threshold may be determined from a percentilevalue based on the expected work level (e.g., the threshold may be setat the 95% ile or 99% ile of a statistical set of expected work levelvalues) or a number-of-standard-deviations value based on the expectedwork level (e.g., the threshold may be set at 2 or 3 standard deviationsabove a measure of central tendency of expected work level). Regardlessof how the threshold is set, the work level threshold may then be usedin detecting seizures based on work level excursions above the thresholdlevel.

FIG. 7B shows another embodiment of determining a work level excursionthreshold at 640 in more detail. A patient state may be determined at710, and a time of day may be determined at 720. This determination isgenerally not needed to establish an extreme work level excursionthreshold, for reasons discussed supra. When activity patterns (by timeof day and/activity type and level) exist, the work level correspondingto it with it may be determined at 730. It should be noted that thecorrelation between work level and activity pattern may be positive ornegative, and strong or weak. If the patient state, activity level ortype, is determined at 740 to deviate from a pattern or historicalactivity, then a maximum acceptable variation of work level based on thepatient state, body data, and/or patient activity may be determined at760. If the patient state or activity level or type do not deviate froma pattern or historical activity type or level as determined at 740,then it may be determined at 750 whether the work level pattern orpatient state (e.g., asleep, resting awake, etc.) is commensurate (i.e.,the observed values are similar to the expected values) with thepatient's activity level. If the work level is commensurate with thepatient's activity level, then flow may proceed to determining at 760the maximum acceptable variation of work level, and determining the worklevel excursion threshold at 765. If the patient state is notcommensurate with the patient's activity level, a seizure may bedetected at 755 from this observation alone.

In one embodiment, the work level threshold is associated with anextreme work level, defined as that associated with body signals valuesat least 3 SD to the right of the mean of body signal values. In yetanother embodiment, the occurrence of simple or complex partial seizureswith motor manifestations either positive (e.g., muscle contractions) ornegative (e.g., lack of movements/motionless) may be determined, basedon the correlation of body signal values and work level.

Returning to FIG. 6, upon determination of at least the first work levelat 620 and at least one work level excursion threshold at 640, the worklevel(s) may be compared at 650 to the threshold(s). If the work levelis determined at 660 to be within the expected range or below athreshold(s), then a non-seizure occurrence may optionally be logged at665 and flow may return to receiving at 610. A non-seizure occurrencemay be further analyzed at a later time based upon additional data(i.e., the manual declaration of a seizure by the patient or thedeclaration of a seizure based upon a different declaration systems) todynamically tune at least one work level excursion threshold.

If the work level is determined at 660 to exceed the work levelexcursion threshold(s), then a seizure or other pathological state maybe declared at 670. If desired, a verification function, such as aconfirmation test, may be performed at 667 prior to the declaration at670. In either event, after declaration at 670, a further action, e.g.,warning the patient, a caregiver, or a medical professional of theseizure or other pathological state; treating the pathological state;logging the pathological state's occurrence or a characteristic thereof;etc., may be performed at 680.

FIG. 8 shows a flowchart representation of a method 800 of determiningan occurrence of an epileptic convulsive seizure (e.g., a primarily orsecondarily generalized tonic seizure, a tonic-clonic seizure, or aclonic-tonic-clonic seizure, among others) in a patient. The method 800may comprise receiving at 810 body data from a patient during a firsttime period. The body data may comprise at least one of kinetic data,oxygen saturation data, blood pH data, oxygen consumption data, glucoseconsumption data, respiratory rate, tidal volume, or end tidal CO₂ data.Kinetic data includes, but is not limited to, force, duration ofcontraction, rate of movement, amplitude of movement, velocity ofmovement, direction of movement, and duration of movement. Kinetic orautonomic data may be used to determine a patient's activity level, andthis activity level may be in turn used to determine (“by proxy”) worklevel. Oxygen saturation data, blood pH data, oxygen consumption data,glucose consumption data, respiratory rate, tidal volume, end tidal CO₂data, or the like may be used to determine work level.

A work level relating to said first time period may be determined at 820based at least partially upon said body data. If the work level isdetermined at 830 to exceed an extreme work level threshold, then one ormore responsive actions may be performed 840, such as determining at 840a the occurrence of a convulsive seizure, or implementing at 840 b aconfirmation test to confirm the occurrence of a convulsive seizure,delivering a therapy, issuing a warning of the occurrence of theseizure, logging the date and time of occurrence of the seizure,determining a response to said therapy, determining an adverse effect ofsaid therapy, determining a severity of the seizure, or determining ifthe seizure resulted in an injury to the patient, among others.

The confirmation test implemented at 840 b may be a test based oncardiac data of said patient, a test based on respiratory data of saidpatient, a test of the patient's body movements, a test of the patient'sresponsiveness, or a test of the patient's awareness. Alternatively orin addition, in one embodiment, the confirmation test may involve adetermination whether the patient's work level is incommensurate with arange expected for the time of day, week, month, or year, whether thepatient's work level is incommensurate with the patient's activitylevel, or both.

In some embodiments, if desired and/or appropriate, the extreme worklevel threshold may be dynamically adjusted at 850 based at least inpart on one or more of a time of day, environmental conditions (e.g.,time of day, ambient temperature, altitude, ambient humidity, etc.), apatient's body weight and height, a patient's body mass index, apatient's gender, a patient's age, an indicator of said patient'soverall health, a patient's hydration status, or an indicator of saidpatient's overall fitness. For example, in a not-uncommon situation inthe developing world, in a patient having a high fever undercircumstances where the environmental temperature is also quite high, anintense complex partial seizure with a hypermotoric component may giverise to a detectable work level that, in cooler ambient conditionsand/or for a non-febrile patient, would only be possible for aconvulsive seizure. Alternatively or in addition, the extreme work levelthreshold may be determined at 860 based at least partially upon anhistorical indication of the patient's maximal non-pathological worklevel.

Turning now to FIG. 11, this figure shows a method 1000 of detecting theoccurrence of a seizure, according to some embodiments of the presentdisclosure. The method comprises at least receiving at 1005 body datarelating to a patient's work level and determining at 1015 the patient'swork level from the body data.

After determination at 1015 of the patient's work level, in oneembodiment, it may be determined at 1030 whether the patient's worklevel is an extreme work level. If it is an extreme work level, aconvulsive seizure may be declared at 1035. If it is not an extreme worklevel, flow may pass to either or both of determinations 1040 or 1050.

In other embodiments, after determination at 1015 of the patient's worklevel, flow may pass to either or both of determinations 1040 or 1050and omit the determination at 1030.

In one embodiment, the method may comprise receiving at 1002 time/datedata and determining at 1012 the time/date from the time/date data. Inlight of the time/date, an expected work level range may be determinedat 1022. It may then be determined at 1040 if the work level (determinedat 1015) is incommensurate with the work level range expected for thetime/date. If it is incommensurate with the expected work level range, aseizure may be declared at 1052, if confirmation of the seizure is notdesired, or a confirmation of the seizure may be performed at 1055.

For example, confirmation may be not desired if the therapy is safe,lacks side effects, and/or has not exceeded a maximum dosage in acurrent time window; if sensitivity, speed of detection, or both aredesirable; if specificity is not particularly desirable; if the seizurehas low intensity; or the like. For example, if a patient has partialseizures with secondary generalization (invariably associated with fallsto the ground) that are abated if therapy is delivered within 5 sec ofelectrographic onset (while the patient is still aware and responsive),sensitivity and speed of detection may be maximized by omitting aconfirmation of the declaration at 1052. Doing so may reduce theprobability of serious injuries should the patient have a seizure.

On the other hand, confirmation may be desired if the therapy hasunwelcome side effects; if specificity is desirable; if the drug supply(e.g., of a therapeutic drug administered automatically from a drugreservoir) or the battery life (e.g., of an electrical therapy device)is low. For example, if a patient with partial seizures with secondarygeneralization is lying in bed, and uses an anti-seizure therapy whichis efficacious, but associated with intolerable side effects,specificity, not sensitivity or speed of detection, is paramount. Hence,a confirmation at 1055 of the seizure may be desirable. In oneembodiment, the method may comprise receiving at 1004 activity leveldata regarding the patient and determining the patient's activity levelat 1014. In light of the patient's activity level, an expected worklevel range may be determined at 1024. It may then be determined at 1050if the work level (determined at 1015) is incommensurate with the worklevel range expected for the patient's activity level. If it isincommensurate with the expected work level range, a seizure may bedeclared at 1052, if confirmation is not desired, or a confirmation of aseizure may be performed at 1055. More specifically, if said observedwork level is incommensurate with the activity level at the time of themeasurement, but is within the physiological range, the epilepticseizure may be classified as partial and if the work level is above theupper range for non-ictal/physiological activity (e.g., it reaches or isabove the extreme threshold) the seizure may be classified as epilepticconvulsive.

A confirmation of a seizure may be performed at 1055 using techniquesdescribed elsewhere herein, described in other patents or applicationsto Cyberonics, Inc., or Flint Hills Scientific, LLC incorporated byreference herein, or known to the person of ordinary skill in the arthaving the benefit of the present disclosure. After performing aconfirmation at 1055, if it is determined at 1060 that a seizure isconfirmed, a seizure may be declared at 1065, if the extreme work levelhas not been reached or exceed and if the work level is not commensuratewith the activity level.

If a seizure is declared at 1052, or it is determined at 1060 that aseizure is not confirmed, then flow may return to receiving body data at1005, receiving time/date data at 1002, and/or receiving activity leveldata at 1004. Flow may also return to one or more of elements 1005,1002, or 1004 upon a “NO” result for the determinations at 1030, 1040,and/or 1050.

Turning now to FIG. 9A, this figure shows a method 900 a of determininga work level of a subject's body or a part thereof, which may be asfollows. The method may comprise determining at 910 a first oxygensaturation, concentration, or pressure of the subject's blood at a firstlocation. The method may comprise determining at 920 a second oxygensaturation, concentration, or pressure of the subject's blood at asecond location. In some embodiments, the method may comprisedetermining at 925 a difference or a ratio between the first oxygensaturation, concentration, or pressure and the second oxygen saturation,concentration, or pressure. A difference determined at 925 can bedetermined simply by subtracting the second oxygen saturation,concentration, or pressure from the first, or vice versa and alsoencompasses determining the absolute value of the result of subtraction,should the result of subtraction be negative. A ratio determined at 925can be determined simply by dividing the second oxygen saturation,concentration, or pressure by the first, or vice versa. The method maycomprise determining at 930 the work level of the subject's body or partthereof based on the first and second oxygen saturation, concentration,or pressures and/or the difference between them.

In some embodiments, the first location is in a carotid artery; thesecond location is in a jugular vein; and the body part is the patient'sbrain. The first location and the second location may be located on afirst side of the patient's body. This embodiment may be useful fordetection of partial seizures, by measuring energy consumption of thebrain. In other words, in some embodiments, the difference in oxygensaturation, concentration, or pressure between a carotid artery and anipsilateral jugular vein may be used to detect the occurrence of partialseizures in patient with epilepsy.

It should be noted that, although the description so far has focused ongathering oxygen information of the anterior (e.g., carotid)circulation, the person of ordinary skill in the art would understandthat the same method and procedure could be applied to the posteriorcirculation (vertebral arteries and branches thereof and posteriorvenous sinuses) to yield other information useful in determining a worklevel for the patient's brain, one or more parts thereof, the patient'sbody, or one or more parts thereof.

Turning to FIG. 9B, which depicts a method 900 b which has many likeelements with FIG. 9A that will not be further described, someembodiments may comprise one or more of determining at 912 a thirdoxygen saturation, concentration, or pressure of the subject's blood ata third location, determining at 922 a fourth oxygen saturation,concentration, or pressure of the subject's blood at a fourth location,determining at 927 a difference between the third oxygen saturation,concentration, or pressure and the fourth oxygen saturation,concentration, or pressure, or determining at 932 the work level of thesubject's body or part thereof based on the third and fourth oxygensaturation, concentration, or pressures and/or the difference betweenthem.

Thus, in some embodiments, the method 900 b may comprise determining thework level of at least two regions of the subject's brain. In oneembodiment, the at least two regions are the left and right hemispheresof the brain. In other embodiments, two or more of the at least tworegions may be within the same hemisphere. The work level of the atleast two regions of the subject's brain may be determinedsimultaneously, may be determined for overlapping time periods, or maybe determined for non-overlapping time periods.

In embodiments comprising simultaneous bilateral measurements of oxygenconsumption (e.g., the left carotid artery may be the first location,the left jugular vein may be the second location, the right carotidartery may be the third location, and the right jugular vein may be thefourth location), such bilateral measurements may provide informationregarding the unilaterality or bilaterality of seizures, the side ofseizure origin, and the time of spread (if any) to the contralateralbrain region. Bilateral measurements may also help distinguish partialfrom generalized and for the latter, primarily v. secondarilygeneralized. For seizures associated with movements of most or all bodyparts, oxygen consumption measurements may help distinguish epilepticfrom non-epileptic (psychogenic, “pseudo-seizures”) seizures.Measurements of oxygen consumption of certain brain regions (e.g.,occipital lobes) not supplied by the carotid system, may be performedfrom posterior circulation system.

In some embodiments, the first location is in a blood vessel selectedfrom a left ventricle, an aorta, a branch of the aorta (e.g., carotidartery), or a sub-branch of the aorta (e.g., middle cerebral artery);the second location is in a superior vena cava, an inferior vena cava, aright ventricle, a pulmonary artery, a jugular vein or a cerebral venoussinus; and the work level is determined of the subject's body.

In other embodiments the difference in oxygen saturation, concentration,or pressure between systemic or body arterial blood (which may bemeasured, for example, in the left ventricle) and systemic or bodyvenous blood (which may be measured, for example, in the rightventricle) may be used to determine if the patient had an epilepticconvulsion.

In some embodiments, information regarding work level may be determinedby use of a single oxygen saturation, concentration, or pressuremeasurement at a single location, if compared to an appropriate control.In one embodiment, the oxygen saturation, concentration, or pressuremeasured at the first location may be compared with a negative control,i.e., an oxygen saturation, concentration, or pressure measured at thefirst location during a verified non-seizure state. In anotherembodiment, the oxygen saturation, concentration, or pressure measuredat the first location may be compared with a positive control, i.e., anoxygen saturation, concentration, or pressure measured at the firstlocation during a verified seizure state, such as partial seizure or aconvulsive seizure. This embodiment may allow determinations of worklevel by use of only one oxygen saturation, concentration, or pressuresensor.

In yet another embodiment, a difference in the difference in arterialand venous blood oxygen saturation, concentration, or pressure asmeasured in a carotid artery and jugular vein compared to that measuredin a right and left ventricles may be used to determine if the patienthad a convulsion or a partial seizure.

In yet another embodiment, a bilateral difference between (i) thedifference in oxygen saturation, concentration, or pressure measured inthe left carotid artery and the left jugular vein and (ii) thedifference in oxygen saturation, concentration, or pressure measured inthe right carotid artery and the right jugular vein may be used todetermine if the patient had a unilateral or a bilateral partialseizure. In other words, the difference between the oxygen saturation,concentration, or pressure differences may be determined (e.g., at FIG.9B, 940). This embodiment may be particularly useful regarding seizureshaving an origin in the mesiotemporal lobe.

The methods depicted in FIGS. 6-9 and 11 and/or described above may begoverned by instructions that are stored in a non-transitory computerreadable storage medium and that are executed by, e.g., a processor 217of the medical device 200. Each of the operations shown in FIGS. 6-9 and11 and/or described above may correspond to instructions stored in anon-transitory computer memory or computer readable storage medium. Invarious embodiments, the non-transitory computer readable storage mediumincludes a magnetic or optical disk storage device, solid state storagedevices such as flash memory, or other non-volatile memory device ordevices. The computer readable instructions stored on the non-transitorycomputer readable storage medium may be in source code, assemblylanguage code, object code, or other instruction format that isinterpreted and/or executable by one or more processors.

In some embodiments, the present disclosure relates to one or more ofthe following numbered paragraphs:

101. A non-transitory computer readable program storage unit encodedwith instructions that, when executed by a computer, perform a method ofdetermining an occurrence of an epileptic seizure in a patient,comprising:

receiving body data from a patient during a first time period,

determining a work level relating to said first time period at leastbased partially upon said body data;

determining an activity level of said patient during said first timeperiod;

determining whether said work level is incommensurate with said activitylevel; and

determining said occurrence of said epileptic seizure, based at least inpart on said incommensurateness of said work level with said activitylevel.

102. The non-transitory computer readable program storage unit ofnumbered paragraph 101, further comprising: determining if saidincommensurate work level reaches or exceeds an extreme work level,classifying said epileptic seizure as partial if said incommensuratework level does not reach or exceed an extreme work level threshold andclassifying said seizure as convulsive if said work level reaches orexceeds an extreme work level threshold.

103. The non-transitory computer readable program storage unit ofnumbered paragraph 101, further comprising implementing a confirmationtest of said epileptic seizure in response to said work level beingincommensurate with said activity level, and confirming said occurrenceof said epileptic seizure based at least in part on a result of saidconfirmation test.

104. The non-transitory computer readable program storage unit ofnumbered paragraph 101, wherein determining said activity levelcomprises:

determining at least one environmental condition selected from time ofday, temperature, humidity, or altitude;

and receiving patient body data relating to at least one of currentkinetic activity, current cognitive activity, or current emotionalactivity.

105. The non-transitory computer readable program storage unit ofnumbered paragraph 101, wherein determining whether said work level isincommensurate with said activity level comprises:

determining an expected work level based on the activity level; and

comparing said work level and said expected work level.

106. The non-transitory computer readable program storage unit ofnumbered paragraph 105, wherein determining said expected work level isbased at least in part on at least one of a patient state, saidpatient's body weight and height, said patient's body mass index, saidpatient's gender, said patient's age, said patient's hydration status,an indicator of said patient's overall health, an indicator of saidpatient's overall fitness, or a determination that said patient staterelating to said time of day corresponds with a patient's historicalactivity.

107. The non-transitory computer readable program storage unit ofnumbered paragraph 106, wherein determining said patient state comprisesperforming at least one of:

receiving a patient body data indicative of said patient state; or

performing a correlation between said body data and at least one of aplurality of candidate states, and selecting at least one of saidcandidate states as the patient state based upon said correlation.

108. The non-transitory computer readable program storage unit ofnumbered paragraph 107, wherein performing said correlation between saidbody data and at least one of said plurality of candidate statecomprises performing a lookup of said plurality of candidates based uponsaid body data.

109. The non-transitory computer readable program storage unit ofnumbered paragraph 101, further comprising confirming said occurrence isbased on at least one of: a work level incommensurate with a work levelrange expected for the patient at the time of day, week, month, season,or year of occurrence, level of activity or said work level exceeding anextreme work level at the time of occurrence.

110. The non-transitory computer readable program storage unit ofnumbered paragraph 109, wherein initiating said confirming comprisesexamining at least one of a cardiac data, a respiratory data, an oxygensaturation data, a metabolic data, or an endocrine data to confirm saidpathological state.

111. The non-transitory computer readable program storage unit ofnumbered paragraph 110, wherein said body data comprises at least one ofkinetic data, oxygen saturation data, blood pH data, oxygen consumptiondata, glucose consumption data, respiratory rate, tidal volume, or endtidal CO2 data.

112. The non-transitory computer readable program storage unit ofnumbered paragraph 101, further comprising determining a non-seizurework level range, wherein said non-seizure work level range is based atleast in part on one or more of a time of day, environmental conditions,a patient's body weight and height, said patient's body mass index, saidpatient's gender, said patient's age, said patient's hydration status,an indicator of said patient's overall health, or an indicator of saidpatient's overall fitness.

113. The non-transitory computer readable program storage unit ofnumbered paragraph 109, wherein said confirmation test is selected froma test based on cardiac data of said patient, a test based onrespiratory data of said patient, a test of the patient's bodymovements, a test of the patient's responsiveness, or a test of thepatient's awareness.

201. A non-transitory computer readable program storage unit encodedwith instructions that, when executed by a computer, perform a method ofdetermining an occurrence of an epileptic seizure in a patient during afirst time period, comprising:

determining a work level relating to said first time period;

determining an expected work level range during said first time period;

determining whether said work level is incommensurate with said expectedwork level range during said first time period; and

determining said occurrence of said epileptic seizure, based at least inpart on said work level being incommensurate with said expected worklevel range during said first time period.

202. The non-transitory computer readable program storage unit ofnumbered paragraph 201, further comprising implementing a confirmationtest of said epileptic seizure in response to said work level beingincommensurate with said expected work level range, and whereindetermining said occurrence of said epileptic seizure is based at leastin part on a result of said confirmation test.

203. The non-transitory computer readable program storage unit ofnumbered paragraph 201, wherein determining said expected work levelrange is based at least in part on a time of day, week, month, season,or year comprised by said first time period.

204. The non-transitory computer readable program storage unit ofnumbered paragraph 201, further comprising confirming said occurrence isbased on at least one of: said work level exceeding an extreme worklevel at the time of occurrence; or a work level incommensurate with awork level range expected for the patient based on the patient'sactivity level at the time of occurrence.

205. The non-transitory computer readable program storage unit ofnumbered paragraph 202, wherein said confirmation test is selected froma test based on cardiac data of said patient, a test based onrespiratory data of said patient, a test of the patient's bodymovements, a test of the patient's responsiveness, or a test of thepatient's awareness.

301. A non-transitory computer readable program storage unit encodedwith instructions that, when executed by a computer, perform a method ofdetermining an occurrence of an epileptic seizure in a patient,comprising at least two of:

determining a work level incommensurate with a work level range expectedfor the patient at least one temporal occurrence at one of a time ofday, week, month, season, or year of occurrence;

determining a work level exceeding an extreme work level at a time ofoccurrence of said epileptic seizure; or

determining a work level incommensurate with the patient's activitylevel at the time of occurrence.

401. A non-transitory computer readable program storage unit encodedwith instructions that, when executed by a computer, perform a method ofclassifying a seizure in a patient, comprising at least one of:

determining a seizure to be an epileptic seizure based on determining atleast one of:

a work level incommensurate with a work level range expected for thepatient for at least one temporal window from one of a time of day,week, month, season, or year of occurrence;

a work level exceeding an extreme work level at a time of occurrence ofsaid seizure; or

a work level incommensurate with the patient's activity level at thetime of occurrence; or

determining an epileptic seizure to be a convulsive seizure based ondetermining a work level exceeding an extreme work level at a time ofoccurrence of said seizure, or a determining an epileptic seizure to benon-convulsive based on the work level during said seizure beingincommensurate with the patient's activity level at the time ofoccurrence, but not exceeding an extreme work level threshold.

501. A non-transitory computer readable program storage unit encodedwith instructions that, when executed by a computer, perform a method ofdetermining an occurrence of an epileptic convulsive seizure in apatient, comprising:

receiving body data from a patient during a first time period;

determining a work level relating to said first time period at leastbased partially upon said body data;

determining whether said work level exceeds an extreme work levelthreshold;

performing a responsive action, in response to a determination that saidwork level exceeds said extreme work level threshold, wherein saidresponsive action is selected from:

determining said occurrence of said convulsive seizure, or

implementing a confirmation test to confirm said occurrence of saidconvulsive seizure.

502. The non-transitory computer readable program storage unit ofnumbered paragraph 501, wherein said body data comprises at least one ofkinetic data, oxygen saturation data, blood pH data, oxygen consumptiondata, glucose consumption data, or end tidal CO₂ data

503. The non-transitory computer readable program storage unit ofnumbered paragraph 501, wherein said confirmation for said occurrence isselected from a test based on cardiac data of said patient, a test basedon respiratory data of said patient, a test of the patient's bodymovements, a test of the patient's responsiveness, or a test of thepatient's awareness.

504. The non-transitory computer readable program storage unit ofnumbered paragraph 501, further comprising dynamically adjusting saidextreme work level threshold, based at least in part on one or more of atime of day, environmental conditions, a patient's body weight andheight, said patient's body mass index, said patient's gender, saidpatient's age, said patient's hydration status, an indicator of saidpatient's overall health, or an indicator of said patient's overallfitness.

505. The non-transitory computer readable program storage unit ofnumbered paragraph 501, wherein determining said extreme work levelthreshold comprises determining said extreme work level threshold basedat least partially upon an historical indication of the patient'smaximal non-pathological work level.

506. A medical device system, comprising:

at least one sensor, each configured to collect at least one body signalfrom a patient relating to a work level of said patient; and

a medical device, comprising:

a body data module configured to receive body data;

a patient state data unit configured to determine the patient statebased upon said body data;

a work level data module configured to determine a patient's first worklevel during a first time period, and the patient's second work levelduring a second time period;

a work level excursion module configured to determine a work levelexcursion threshold based at least one said body data, time of day, orsaid patient state; and

a work level excursion test module configured to determine whether saidsecond work level exceeds said first work level greater by than anamount of said first work level excursion threshold; and

a controller to perform at least one of warning of a pathological state,providing a therapy, or logging said occurrence of said pathologicalstate.

507. The medical device system of numbered paragraph 506, wherein saidmedical device is configured to perform a test based on cardiac data ofsaid patient, a test based on kinetic data of said patient, a test ofthe patient's responsiveness, or a test of the patient's awareness toconfirm said pathological state.

508. The medical device system of numbered paragraph 506, wherein saidnon-pathological work level range module is configured to determine anon-pathological work level range of said patient, further based atleast in part on one or more of a time of day, an indicator of saidpatient's overall health, an indicator of said patient's overallfitness, a patient's body weight and height, a patient's body massindex, a patient's gender, or a patient's age.

509. The medical device system of numbered paragraph 506, wherein saidwork level data module comprises:

a body data analysis module to determine a value relating to at leastone of a cardiac data, blood pressure data, respiration data, blood gasdata, patient kinetic data, responsiveness data, endocrine data,metabolic data, or tissue stress marker data; and

a work level determination unit to determine said first and secondpatient work levels based upon at least one of said cardiac data, bloodpressure data, respiration data, blood gas data, patient kinetic data,responsiveness data, endocrine data, metabolic data, or tissue stressmarker data.

510. The medical device system of numbered paragraph 506, wherein saidpatient state module comprises:

a background activity time period module configured to provide datarelating to historic patient activity in relation to time of day;

a body data activity correlation unit configured to correlate said bodydata to at least one of a plurality of candidate states based upon saiddata relating to historic patient activity; and

a patient input unit configured to receive and input from said patient.

511. The medical device system of numbered paragraph 506, furthercomprising:

a warning unit to provide a warning in response to a determine that apathological state has occurred;

a therapy unit configured to provide a therapy in response to adetermine that a pathological state has occurred; and

a logging unit to log an occurrence of said pathological state.

512. The medical device system of numbered paragraph 506, wherein saidat least one sensor comprises at least one of:

an autonomic data acquisition unit configured to acquire at least one ofheart beat data, blood pressure data, respiration data, or blood gasdata;

a neurological data acquisition unit configured to acquire kinetic dataselected from the group consisting of accelerometer data andinclinometer data.

an endocrine data acquisition unit configured to acquire endocrine data,

a metabolic data acquisition unit configured to acquire metabolic data;

a tissue stress marker data acquisition unit configured to acquiretissue stress marker data;

a physical fitness data acquisition unit configured to acquire datarelating to the patient's physical fitness; or

an environmental conditions sensor configured to acquire data relatingto at least one of time of day, ambient temperature, altitude, ambienthumidity, barometric pressure, or luminance.

513. A medical device, comprising:

a body data module configured to receive body data;

a patient state data configured to determine the patient state basedupon said body data;

a work level data module configured to determine a first patient worklevel during a first time period, and a second patient work level duringa second time period;

a work level excursion module configured to determine a work levelexcursion threshold based at least one said body data, time of day, orsaid patient state; and

a work level excursion test module configured to determine whether saidsecond work level exceeds said first work level by at least said firstwork level excursion threshold; and

a controller to perform at least one of warning of a pathological state,providing a therapy, or logging said pathological state, in response toa determination that said second work level exceeds said first worklevel greater by than an amount of said first work level excursionthreshold.

514. The medical device of numbered paragraph 513, further comprising:

a warning unit to provide a warning in response to a determine that apathological state has occurred;

a therapy unit configured to provide a therapy in response to adetermine that a pathological state has occurred; and

a logging unit to log an occurrence of said pathological state.

515. The medical device system of numbered paragraph 513, wherein saidpathological state is an epileptic event.

516. A non-transitory computer readable program storage unit encodedwith instructions that, when executed by a computer, perform a method ofdetermining a work level of a subject's brain, comprising:

determining a first oxygen saturation of the subject's blood at a firstlocation in a carotid artery;

determining a second oxygen saturation of the subject's blood at asecond location in a jugular vein;

determining a difference between the first oxygen saturation and thesecond oxygen saturation; and

determining the work level of the subject's brain based on thedifference.

517. A medical device system, comprising:

a first sensor configured to collect first oxygen saturation data of asubject's blood from a first location in a carotid artery;

a second sensor configured to collect second oxygen saturation data ofthe subject's blood from a second location in a jugular vein; and

a medical device, comprising:

a first location oxygen saturation module configured to determine afirst oxygen saturation from said first oxygen saturation data;

a second location oxygen saturation module configured to determine asecond oxygen saturation from said second oxygen saturation data;

an oxygen saturation difference module configured to determine adifference between the first oxygen saturation and the second oxygensaturation; and

a brain work level determination module configured to determine a worklevel of the subject's brain based on the difference.

518. A non-transitory computer readable program storage unit encodedwith instructions that, when executed by a computer, perform a method ofdetermining a work level of a subject's body, comprising:

determining a first oxygen saturation of the subject's blood at a firstlocation in a blood vessel selected from a left ventricle of a heart;

determining a second oxygen saturation of the subject's blood at asecond location in a right ventricle of a heart;

determining a difference between the first oxygen saturation and thesecond oxygen saturation; and

determining the work level of the subject's body based on thedifference.

519. A medical device system, comprising:

a first sensor configured to collect oxygen saturation data of asubject's blood from a first location selected from at least one of anascending aorta or a left ventricle;

a second sensor configured to collect second oxygen saturation data ofthe subject's blood from a second location in an inferior vena cava; and

a medical device, comprising:

at least one oxygen saturation modules configured to determine oxygensaturation from said first sensor and said second sensor;

an oxygen saturation difference module configured to determine an oxygensaturation difference between said first sensor and said second sensor;and

a seizure classification module to classify a seizure as one of anon-epileptic seizure, a convulsive epileptic seizure or anon-convulsive epileptic seizure based upon said output from said oxygensaturation module.

520. The medical device system of numbered paragraph 506, wherein saidpatient state module determines a patient state based upon body data.

601. A non-transitory computer readable program storage unit encodedwith instructions that, when executed by a computer, perform a method ofdetermining a work level of a subject's body or a part thereof,comprising:

determining a first oxygen saturation, concentration, or pressure of thesubject's blood at a first location in a blood vessel selected from aleft ventricle, an aorta, a branch of the aorta, or a sub-branch of theaorta;

determining a second oxygen saturation, concentration, or pressure ofthe subject's blood at a second location in a superior vena cava, aninferior vena cava, a right ventricle, or a pulmonary artery;

and

determining the work level of the subject's body or the part thereofbased on the first oxygen saturation, concentration, or pressure and thesecond oxygen saturation, concentration, or pressure.

602. The non-transitory computer readable program storage unit ofnumbered paragraph 601, wherein the method further comprises determininga difference or a ratio between the first oxygen saturation,concentration, or pressure and the second oxygen saturation,concentration, or pressure.

603. A medical device system, comprising:

a first sensor configured to collect first oxygen saturation,concentration, or pressure data of a subject's blood from a firstlocation in a blood vessel selected from a left ventricle, an aorta, abranch of the aorta, or a sub-branch of the aorta;

a second sensor configured to collect second oxygen saturation,concentration, or pressure data of the subject's blood from a secondlocation in a superior vena cava, an inferior vena cava, a rightventricle or a pulmonary artery; and

a medical device, comprising:

a first location oxygen saturation, concentration, or pressure moduleconfigured to determine a first oxygen saturation, concentration, orpressure from said first oxygen saturation, concentration, or pressuredata;

a second location oxygen saturation, concentration, or pressure moduleconfigured to determine a second oxygen saturation, concentration, orpressure from said second oxygen saturation, concentration, or pressuredata; and

a brain work level determination module configured to determine a worklevel of the subject's body based on the first oxygen saturation,concentration, or pressure and the second oxygen saturation,concentration, or pressure.

604. The medical device system of numbered paragraph 603, wherein themedical device further comprises

an oxygen saturation, concentration, or pressure difference moduleconfigured to determine a difference or a ratio between the first oxygensaturation, concentration, or pressure and the second oxygen saturation,concentration, or pressure.

701. A method of determining a work level of a patient's body or a partthereof, comprising:

determining at least one cardiac signal from said patient; and

determining said work level, based on said at least one cardiac signal.

702. The method of claim 701, wherein the at least one cardiac signal isa heart rate of said patient.

What is claimed:
 1. A medical device, comprising: a body data moduleconfigured to receive body data from a patient; a work level data moduleconfigured to determine a first work level for the patient during afirst time period, and a second work level for the patient during asecond time period; a work level excursion module configured to:determine whether the second work level exceeds the first work level byan amount greater than a first work level excursion threshold whichindicates that the second work level has a current body signal valuewhich is incommensurate to an expected body signal value range for thesecond work level; and detect a work level excursion based upon thedetermination that the current body signal value for the second worklevel is incommensurate to the expected body signal value range for thesecond work level which indicates an epileptic seizure event; and acontroller configured to perform at least one of generating a warning ofthe epileptic seizure event, providing a therapy for the epilepticseizure event, or logging an occurrence of the epileptic seizure event,in response to detecting the work level excursion.
 2. The medical deviceof claim 1, wherein the first time period is at a first time of day on acurrent day and the second time period is at the first time of day on atleast one prior day.
 3. The medical device of claim 1, wherein the firsttime period and the second time period are contiguous, partiallyoverlapping, or fully overlapping.
 4. The medical device of claim 1,wherein the first work level and the second work level are each a worklevel magnitude or a work level rate of change.
 5. The medical device ofclaim 1, further comprising: at least one sensor, each configured tocollect at least one body signal from the patient relating to a worklevel of the patient.
 6. The medical device of claim 5, wherein the atleast one sensor comprises at least one of: an autonomic dataacquisition unit configured to acquire at least one of heart beat data,blood pressure data, respiration data, or blood gas data; a neurologicaldata acquisition unit configured to acquire kinetic data selected fromthe group consisting of accelerometer data and inclinometer data; anendocrine data acquisition unit configured to acquire endocrine data, ametabolic data acquisition unit configured to acquire metabolic data; atissue stress marker data acquisition unit configured to acquire tissuestress marker data; or a physical fitness data acquisition unitconfigured to acquire data relating to the patient's physical fitness.7. The medical device of claim 1, further comprising a patient statedata unit configured to determine the patient state based upon the bodydata.
 8. The medical device of claim 1, wherein the medical device isconfigured to confirm the pathological state based on at least one ofcardiac data of the patient, kinetic data of the patient, the patient'sresponsiveness, or a patient's awareness.
 9. The medical device of claim1, wherein the work level excursion threshold is based at least in parton one or more of a time of day, an environmental condition, anindicator of the patient's overall health, an indicator of the patient'shydration status, an indicator of the patient's overall fitness, thepatient's body weight and height, the patient's body mass index, thepatient's gender, or the patient's age.
 10. The medical device of claim1, wherein the work level data module comprises: a body data analysismodule to determine a value relating to at least one of a cardiac data,a blood pressure data, a respiration data, a blood gas data, a patientkinetic data, a responsiveness data, an endocrine data, a metabolicdata, or a tissue stress marker data; and a work level determinationunit to determine the first work level and the second work level basedupon at least one of the cardiac data, the blood pressure data, therespiration data, the blood gas data, the patient kinetic data, theresponsiveness data, endocrine data, the metabolic data, or the tissuestress marker data.
 11. The medical device of claim 10, wherein the worklevel excursion module is further configured to determine the first worklevel excursion threshold based on at least one of the body data, a timeof day, or a patient state.
 12. The medical device of claim 11, furthercomprising a patient state module configured to determine the patientstate based upon the body data.
 13. The medical device of claim 10,further comprising: a background activity time period module configuredto provide data relating to historic patient activity in relation totime of day; a body data activity correlation unit configured tocorrelate the body data to at least one of a plurality of candidatestates based upon the data relating to historic patient activity; and apatient input unit configured to receive input from the patient.
 14. Themedical device of claim 10, wherein the work level excursion module isfurther configured to determine the first work level excursion thresholdbased at least one on the body data, a time of day, or the patientstate.
 15. The medical device of claim 1, wherein the work levelexcursion is pathological.
 16. The medical device of claim 1, furthercomprising: a warning unit to provide a warning in response to adetermine that the work level excursion has occurred; and a logging unitto log at least one of an occurrence or a severity of the work levelexcursion, wherein logging comprises storing to memory one or more of: adate, a time, or a severity of the epileptic seizure event; a type oftherapy delivered to treat the epileptic seizure event; or at least oneeffect of a therapy delivered to treat the epileptic seizure event. 17.The medical device of claim 1, further comprising a therapy deliverysource configured to deliver an electrical stimulation, a drug, or athermal therapy to a tissue of the patient, in response to adetermination that the work level excursion has occurred.
 18. A medicaldevice, comprising: a body data module configured to receive body datafrom a patient; a work level data module configured to determine a firstpatient work level during a first time period and a second patient worklevel during a second time period; a work level excursion moduleconfigured to: determine whether the second work level exceeds the firstwork level by an amount greater than a first work level excursionthreshold which indicates a first state; and determine a change in bodydata from the first work level to the second work level; and acontroller configured to perform at least one of generating a warning,providing a therapy, or logging data related to the first state when thechange in the body data is not commensurate with the second work level,the controller further configured to suppress the warning and thetherapy when the change in the body data is commensurate with the secondwork level, the controller further configured to log data relating to atleast one of the first work level, the second work level, and the changein the body data when the change in the body data is commensurate withthe second work level.
 19. The medical device of claim 18, furthercomprising a therapy delivery source configured to deliver an electricalstimulation, a drug, or a thermal therapy to a tissue of the patient.20. The medical device of claim 18, wherein a force sensing unit isconfigured to determine a change in kinetic data from the first worklevel to the second work level, the controller configured to perform atleast one of generating the warning, providing the therapy, or loggingdata related to the first state when the change in the kinetic data isnot commensurate with the second work level, the controller furtherconfigured to suppress the warning and the therapy when the change inthe kinetic data is commensurate with the second work level, thecontroller further configured to log data relating to at least one ofthe first work level, the second work level, and the change in thekinetic data when the change in the kinetic data is commensurate withthe second work level.
 21. A medical device, comprising: a body datamodule configured to receive body data from a patient; a work level datamodule configured to determine a first work level for the patient duringa first time period and a second work level for the patient during asecond time period; a work level excursion module configured to:determine whether the second work level does not exceed the first worklevel by an amount greater than a first work level excursion threshold;determine if the body signal value correlated with the second work levelnot exceeding the first work level by the amount greater than the firstwork level excursion threshold is incommensurate with the second worklevel; and when the body signal value is incommensurate with the secondwork level not exceeding the first work level by the amount greater thanthe first work level excursion threshold which indicates an epilepticseizure event, perform via a controller at least one of generating awarning of the epileptic seizure event, providing a therapy for theepileptic seizure event, or logging an occurrence of the epilepticseizure event.
 22. A medical device, comprising: a body data moduleconfigured to receive body data from a patient; a work level data moduleconfigured to determine a first work level for the patient during afirst time period and a second work level for the patient during asecond time period; a work level excursion module configured to:determine whether the second work level does not exceed the first worklevel by an amount greater than a first work level excursion thresholdwhich is associated with a first body signal value; determine if achange in the first body signal value associated with the second worklevel is outside of a range; and determine an epileptic seizure when adetermination that the change in the first body signal value is outsideof the range and occurred during the second time period; and acontroller configured to perform at least one of generating a warning ofthe epileptic seizure, providing a therapy for the epileptic seizure, orlogging an occurrence of the epileptic seizure.